The automotive industry has made significant inroads into the practical development of steer-by-wire technology. Steer-by-wire technology involves steering systems for motorized vehicles utilizing electronically controlled steering components. Currently, a wide variety of advancements have been developed for these control systems. These advancements often seek to improve the driver's control over such steer-by-wire systems as well as improve the feel and feedback of such systems such that the driver retains a level of sensory control similar to that experienced in the prior pure mechanical systems.
One approach to steer-by-wire component design has been to develop electronic components that attach to relatively standard steering wheels and steering column shafts. These components, such as magnetic resistance devices, are used to provide resistance to the steering wheel, monitor steering wheel position, and provide road feel. These components often try to additionally incorporate self-centering characteristics into the steering system. Considerable time and effort has been involved in attempting to design these components to simulate the feel of a mechanical system. It has proven difficult, however, to provide a realistic mechanical feel in such systems when most mechanical linkages have been removed.
In addition to the difficulties in providing realistic mechanical feel to the steering system, present steer-by-wire systems can also suffer from the use of steering column shafts similar to those used in mechanical systems. These steering column shafts are typically solid devices fabricated with relatively high strength and weight. While these characteristics may be a necessity in mechanically operated systems, their use may not be appropriate in steer-by-wire systems where their extra strength may not be necessary and their additional weight is unwarranted. The weight detriment of the steering column shaft may be further exacerbated when the weight of components providing resistance, position monitoring, and feedback are mounted to the steering column.
Instead of developing complex electronic components to be mounted to relatively standard steering column shafts, it may be more beneficial to redesign the steering column shaft itself to incorporate some, if not all, of the features normally provided by external components in a steer by wire system. In this way, the functionality of the steering column shaft may be significantly improved, and it may be possible to reduce the weight of the overall steering system. The steering column shaft may also be designed to incorporate functional characteristics that impart a more realistic mechanical feel to the operator.
It would, therefore, be highly desirable to have an improved steering column shaft for use in a steer-by-wire system with improved functional efficiency by incorporating functionality previously supplied by externally mounted components. It would further be highly desirable to have a steering column shaft for use in a steer by wire system that provided improved mechanical feel to the driver-operator.